343GS is a computerized mechanism, right? Well, why can't he just gain access to the Halo core and corrupt Cortana? He knows that Cortana can get into Master Chief's head (no pun intended) so if he corrupts her, he can very well do what he likes with MC. After all this evidence, I can assume that this is exactly what he tried to do, but something definitely stopped Cortana from corrupting the MC. Now what that something is...